[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE. The purpose of this study was to compare the diagnostic accuracy achieved with and without the calibration method established by the DICOM standard in both medical-grade gray-scale displays and consumer-grade color displays. MATERIALS AND METHODS. This study involved 76 cases, six radiologists, three displays, and two display calibrations for a total of 2736 observations in a multireadermulticase factorial design. The evaluated conditions were interstitial opacities, pneumothorax, and nodules. CT was adopted as the reference standard. One medical-grade gray-scale display and two consumer-grade color displays were evaluated. Analyses of ROC curves, diagnostic accuracy (measured as AUC), accuracy of condition classification, and false-positive and false-negative rate comparisons were performed. The degree of agreement between readers was also evaluated. RESULTS. No significant differences in image quality perception by the readers in the presence or absence of calibration were observed. Similar forms of the ROC curves were observed. No significant differences were detected in the observed variables (diagnostic accuracy, accuracy of condition classification, false-positive rates, false-negative rates, and image-quality perception). Strong agreement between readers was also determined for each display with and without calibration. CONCLUSION. For the chest conditions and selected observers included in this study, no significant differences were observed between the three evaluated displays with respect to accuracy performance with and without calibration.
AJR. American journal of roentgenology. 06/2014; 202(6):1272-80.
[Show abstract][Hide abstract] ABSTRACT: Abstract Introduction: In teleradiology services and in hospitals, the extensive use of visualization displays requires affordable devices. The purpose of this study was to compare three differently priced displays (a medical-grade grayscale display and two consumer-grade color displays) for image visualization of digitized chest X-rays. Materials and Methods: The evaluated conditions were interstitial opacities, pneumothorax, and nodules using computed tomography as the gold standard. The comparison was accomplished in terms of receiver operating characteristic (ROC) curves, the diagnostic power measured as the area under ROC curves, accuracy in conditions classification, and main factors affecting accuracy, in a factorial study with 76 cases and six radiologists. Results: The ROC curves for all of the displays and pathologies had similar shapes and no differences in diagnostic power. The proportion of cases correctly classified for each display was greater than 71.9%. The correctness proportions of the three displays were different (p<0.05) only for interstitial opacities. The evaluation of the main factors affecting these proportions revealed that the display factor was not significant for either nodule size or pneumothorax size (p>0.05). Conclusions: Although the image quality variables showed differences in the radiologists' perceptions of the image quality of the three displays, significant differences in the accuracy did not occur. The main effect on the variability of the proportions of correctly classified cases did not come from the display factor. This study confirms previous findings that medical-grade displays could be replaced by consumer-grade color displays with the same image quality.
Telemedicine and e-Health 02/2014; · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: CONCLUSION
Combined theoretical/on-site programs combined with the latest WEB 2.0 and 3.0 technologies can be key in the training of medical students in diagnostic imaging.
The use of diagnostic imaging has increased significantly on a global scale in the past two decades.Because of this it is essential that medical students acquire more knowledge related to the adequate use of these diagnostic tools, their indications, interpretation of basic findings and patient safety. In Colombia less than 5% of medical schools have a radiology course or clinical rotation. When they do exist, they often end up becoming a rotation where the students sit behind a radiologist listening to him/her dictate studies.
We created a live and virtual 6 weeklong course last year medical students at Los Andes University in Bogotá Colombia. This program was created based on the aims and competencies described by AMSER. The students would have a Problem Based Learning (PBL) session and would have to revise academic reviews on a daily basis in addition to clinical rotations divided by sections. At the same time, students had access to platforms based on WEB 2.0 and WEB 3.0 where they would have the possibility of reviewing podcasts of the classes and answer questions in forums based on practical cases of basic pathologies, which would place the student in the midst of learning and generate discussion among peers creating the concept of collective learning. There were a total of 90 participating students between the years 2009-2012. We applied exams at the beginning and end of the course. The mean of the pre-course exam was 24/100 compared to 85/100 for the post-program exam. A complete statistical analysis was done.
It is necessary to create innovative programs for teaching the basics of Diagnostic Imaging to medical students in order for them to acquire an adequate training in the use and interpretation of these tools due to their ample use in the present world. This is very important in order to ensure the adequate use of medical resources by all practitioners and at the same time will result in benefits and greater safety for patients.
Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
[Show abstract][Hide abstract] ABSTRACT: This study focused on the effects of pneumothorax size quantification in digital radiology environments when a quantification method is selected according to the radiologist's criteria. The objective of this study was to assess the effects of factors, including the radiologist (with different experience), displays (medical-grade and consumer-grade displays), or display calibration, on the Rhea, Collins, and Light quantification methods. This study used a factorial design with 76 cases, including 16 pneumothorax cases observed by six radiologists on three displays with and without the DICOM standard calibration. The gold standard was established by two radiologists by using computed tomography. Analysis of variance (ANOVA) was performed on the pneumothorax sizes. For the three quantifications methods, none of the evaluated factors were significant. We conclude that radiologists, displays, and calibration do not significantly affect the quantification of pneumothorax size in different digital radiology environments.
Journal of Digital Imaging 10/2013; · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Portal biliopathy refers to biliary abnormalities secondary to extrahepatic portal vein obstruction and cavernous transformation and is caused by vascular compression from peribiliary collateral vessels, producing segmental stenoses of the common bile duct and abnormal liver function test (LFT) results. A review of imaging studies yielded 18 patients with abnormal LFT results, biliary tract dilatation, and extrahepatic portal vein obstruction with cavernous transformation. Multidetector computed tomography and magnetic resonance imaging showed biliary stenotic segments in 11 patients secondary to extrinsic compression from enlarged peribiliary collaterals. Clinical and imaging follow-up demonstrated improvement in LFT results with minimal decrease in bile duct dilatation, eliminating percutaneous or endoscopic biliary intervention.
[Show abstract][Hide abstract] ABSTRACT: We assessed the reliability of three digital capture devices: a film digitizer (which cost US $15,000), a flat-bed scanner (US $1800) and a digital camera (US $450). Reliability was measured as the agreement between six observers when reading images acquired from a single device and also in terms of the pair-device agreement. The images were 136 chest X-ray cases. The variables measured were the interstitial opacities distribution, interstitial patterns, nodule size and percentage pneumothorax size. The agreement between the six readers when reading images acquired from a single device was similar for the three devices. The pair-device agreements were moderate for all variables. There were significant differences in reading-time between devices: the mean reading-time for the film digitizer was 93 s, it was 59 s for the flat-bed scanner and 70 s for the digital camera. Despite the differences in their cost, there were no substantial differences in the performance of the three devices.
Journal of telemedicine and telecare 12/2011; 18(2):82-5. · 0.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A common teleradiology practice is digitizing films. The costs of specialized digitizers are very high, that is why there is a trend to use conventional scanners and digital cameras. Statistical clinical studies are required to determine the accuracy of these devices, which are very difficult to carry out. The purpose of this study was to compare three capture devices in terms of their capacity to detect several image characteristics. Spatial resolution, contrast, gray levels, and geometric deformation were compared for a specialized digitizer ICR (US$ 15,000), a conventional scanner UMAX (US$ 1,800), and a digital camera LUMIX (US$ 450, but require an additional support system and a light box for about US$ 400). Test patterns printed in films were used. The results detected gray levels lower than real values for all three devices; acceptable contrast and low geometric deformation with three devices. All three devices are appropriate solutions, but a digital camera requires more operator training and more settings.
Journal of Digital Imaging 05/2011; 25(1):91-100. · 1.10 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Film digitizers are a specialized technology that is available for scanning X-ray radiographs; however, their cost makes them unaffordable for developing countries. Thus, less expensive alternatives are used. The purpose of this study was to compare three devices for digital capture of X-ray films: a film digitizer (US $15,000), a flatbed scanner (US $1800), and a 10-megapixel digital camera (US $450), in terms of diagnostic accuracy, defined as the area under the receiver operating characteristic curves and computed tomography as the gold standard.
The sample included 136 chest X-ray cases with computed tomography confirmation of the presence or absence of pneumothorax, interstitial opacities, or nodules. The readers were six radiologists who made observations of eight variables for each digital capture of the X-ray films: three main variables to determine the accuracy in the detection of the above-mentioned pathologies, four secondary variables to categorize other pathological classifications, and one variable regarding digital image quality.
The receiver operating characteristic curves for each device and pathology were very similar. For the main variables, there was no significant statistical difference in diagnostic accuracy between the devices. For the secondary variables, >84% of cases were correctly classified, even those that were classified with the lowest image quality. High accuracy was determined for the three main variables (0.75 to 0.96), indicating good performance for all tested devices, despite their very different prices.
Choosing a device for a teleradiology service should involve additional factors, such as capture time, maintenance concerns, and training requirements.
Telemedicine and e-Health 04/2011; 17(4):275-82. · 1.40 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hepatic vascular diseases (HVD) are a broad spectrum of entities of low prevalence but with different clinical manifestations that may even lead to death. Its early detection and timely treatment may change the prognosis. Diagnostic imaging plays a key role and imaging findings may be typical. However, in most cases, radiologists must take into account a wide range of differential diagnosis. Computed tomography (CT) of the abdomen is one of the most useful tools for the diagnosis of HVD taking also into account the value of other imaging methods such as Doppler Ultrasound and Magnetic Resonance Imaging (MRI). HVD can be classified according to the compromised vascular structure and can be divided into venous, portal, arterial, sinusoidal and others disorders. The objective of this review is to describe the most common presentation HVD . The major imaging findings and differential diagnosis recognizing its correlation with the pathophysiological mechanisms.
Revista Colombiana de Radiologia. 03/2010; 21(1):2842.
[Show abstract][Hide abstract] ABSTRACT: PURPOSE
Facet joint synovial cysts are not unfrequently responsible for chronic back pain; percutaneous CT-guided procedures have become an important tool for treatment of patients with chronic back pain; this study describes the technique, clinical impact, and complications of CT-guided puncture and infiltration of intraspinal facet joint synovial cysts for management of chronic back pain.
METHOD AND MATERIALS
From Sept-2003 to December-2008, 20 patients with lumbar intraspinal synovial facet joint cysts presenting with chronic back pain were treated percutaneously. CT-guided interventions included a) cyst rupture following direct puncture or pressure injection joint arthrography, and b) infiltration with a combination of steroids and long acting anesthetics. Cyst rupture was confirmed by contrast opacification of the epidural space. Pain intensity was evaluated before and following intervention. Short and long term clinical and imaging follow up was performed.
21 lumbar facet joint cysts were treated in 20 patients (12 women, 8 men, mean age 61.3 years); 14 at the L4-L5 level, 6 at L5 - S1 and 1 at L3-L4. Clinical follow up demonstrated short term resolution of pain symptoms in 18/20 patients (78.5%), and long term improvement in 10/14 (85%); imaging follow up demonstrated significant shrinkage/resolution of synovial cysts in respondent patients. Observed time interval for pain relief was 18 months. 2/4 patients with no long term relief required surgery for pain management. No procedure related complications were seen.
CT-guided percutaneous treatment of intraspinal facet joint synovial cysts constitutes an effective therapy for selected patients with chronic back pain contributing to pain control. This series confirms low complication rate, good response and high therapeutic value. This approach should be considered as an alternative treatment for selected patients with chronic back pain.
CT-guided percutaneous treatment of lumbar intraspinal synovial cysts contributes to pain control in selected patients with chronic back pain and should be considered as an alternative therapy.
Radiological Society of North America 2009 Scientific Assembly and Annual Meeting; 12/2009
[Show abstract][Hide abstract] ABSTRACT: Cirrhotic livers are characterized by advanced fibrosis and the formation of hepatocellular nodules, which are classified histologically as either (a) regenerative lesions (eg, regenerative nodules, lobar or segmental hyperplasia, focal nodular hyperplasia) or (b) dysplastic or neoplastic lesions (eg, dysplastic foci and nodules, hepatocellular carcinomas). The differentiation of these lesions is important because regenerative nodules are benign, whereas dysplastic and neoplastic nodules are premalignant and malignant, respectively. However, their accurate characterization may be difficult even at histopathologic analysis. Differential diagnosis may be facilitated by comparing the clinical and pathologic findings with radiologic imaging features; in particular, nodule size, vascularity, hepatocellular function, and Kupffer cell density assessed at magnetic resonance (MR) imaging are suggestive of the correct diagnosis. MR imaging is more useful than computed tomography for such assessments because it provides better soft-tissue contrast and a more nuanced depiction of different tissue properties. Moreover, a wider variety of contrast agents is available for use in MR imaging. Familiarity with the MR imaging characteristics of cirrhosis-associated hepatocellular nodules is therefore important for optimal diagnosis and management of cirrhotic disease.
[Show abstract][Hide abstract] ABSTRACT: The purpose of our study was to test the hypothesis that, in noncirrhotic livers, large size predicts benignity of masses that homogeneously hyperenhance on arterial phase CT and then fade to isoattenuation.
All multiphasic CT scans obtained at a cancer center over a 2-year period were reviewed. In consensus, three authors retrospectively identified 227 hepatic masses (> or = 5 mm) in 55 noncirrhotic patients that homogeneously hyperenhanced on arterial phase and then faded to isoattenuation: 107 masses were malignant and 120 were benign; 37 patients had benign and 18 patients had malignant masses. Two analytic approaches were pursued: per lesion and per patient. For the per-lesion analysis, the mean cross-sectional diameter of each mass was calculated and receiver operator characteristics (ROC) were assessed. For the per-patient analysis, the maximum lesion diameter was determined for each subject and logistic regression models were used to predict lesion classification (benign vs malignant) based on per-patient maximum lesion size and additional information.
Masses ranged from 5 to 84.5 mm. All 29 masses > or = 22 mm were benign. Size was a statistically significant classifier of benign versus malignant lesions in the per-lesion analysis (p = 0.024, ROC area under the curve) and a significant or trend-level predictor of tumor type in the per-patient analysis (logistic regression p values of the diameter coefficients: 0.01-0.07).
In noncirrhotic livers, relatively large size is a significant or trend-level predictor for benign tumors. Homogeneously hyperenhancing masses > or = 22 mm that fade to isoattenuation are benign; smaller masses may be malignant.
American Journal of Roentgenology 03/2008; 190(2):300-7. · 2.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The major classes of contrast agents currently used for magnetic resonance (MR) imaging of the liver include extracellular agents (eg, low-molecular-weight gadolinium chelates), reticuloendothelial agents (eg, ferumoxides), hepatobiliary agents (eg, mangafodipir), blood pool agents, and combined agents. Mechanisms of action, dosage, elimination, toxic effects, indications for use, and MR imaging technical considerations vary according to class. Gadolinium chelates are the most widely used. Ferumoxides are a useful adjunct for detection of hepatocellular carcinoma, particularly when used in combination with gadolinium to achieve improved lesion-to-liver contrast over that achievable with gadolinium alone. Mangafodipir is a prototype hepatobiliary agent that is taken up by lesions with functioning hepatocytes. It may be used for MR cholangiography as well as liver imaging. Although mangafodipir is no longer commercially available in the United States, it is currently marketed and used in Europe. Blood pool agents have not yet been approved for human use in the United States. However, a new combined MR contrast agent, gadobenate dimeglumine, recently was approved, and other agents are in various stages of development.
[Show abstract][Hide abstract] ABSTRACT: To retrospectively evaluate the accuracy of double contrast material-enhanced (hereafter double-enhanced) magnetic resonance (MR) imaging depiction of hepatic fibrosis, with histopathologic analysis findings as the reference standard.
The institutional review board approved this HIPAA-compliant study and waived the requirement for informed consent. One hundred one patients (58 men, 43 women; mean age +/- standard deviation, 52 years +/- 10) who underwent double-enhanced MR imaging with superparamagnetic iron oxide (SPIO)-enhanced and double-enhanced spoiled gradient-echo (SPGR) sequences between 2001 and 2004 and had a reliable reference standard for the diagnosis of liver fibrosis were included. Two blinded MR radiologists retrospectively scored qualitative (reticulation, nodularity, and total scores) and quantitative (contrast-to-noise ratio between hyperintense and hypointense liver regions, coefficient of variation, and noise-corrected coefficient of variation) liver texture features on MR images in consensus. The image scores for patients with advanced (METAVIR fibrosis score >/= 3) versus those for patients with mild (METAVIR score </= 2) fibrosis were compared, and receiver operating characteristic curves were determined. Diagnostic performance values were calculated at the optimal operating point. Mann-Whitney U and unpaired Student t tests were performed.
Qualitative and quantitative image scores were significantly higher for patients with METAVIR fibrosis scores of 3 or higher than for those with scores of 2 or lower (P < .001); on SPIO-enhanced SPGR images, differences increased with increasing echo time. Diagnostic performance for detection of grade 3 or more severe fibrosis was better with the double-enhanced sequence than with the SPIO-enhanced sequences, and qualitative scores had higher diagnostic performance than quantitative scores. The sensitivity, specificity, and accuracy of qualitative scores on double-enhanced SPGR images were higher than 90%.
Advanced hepatic fibrosis can be detected by using double-enhanced MR imaging. Although diagnostic performance depended on the sequence and scoring system used, sensitivity, specificity, and accuracy values higher than 90% were achievable.
[Show abstract][Hide abstract] ABSTRACT: Fat accumulation is one of the most common abnormalities of the liver depicted on cross-sectional images. Common patterns include diffuse fat accumulation, diffuse fat accumulation with focal sparing, and focal fat accumulation in an otherwise normal liver. Unusual patterns that may cause diagnostic confusion by mimicking neoplastic, inflammatory, or vascular conditions include multinodular and perivascular accumulation. All of these patterns involve the heterogeneous or nonuniform distribution of fat. To help prevent diagnostic errors and guide appropriate work-up and management, radiologists should be aware of the different patterns of fat accumulation in the liver, especially as they are depicted at ultrasonography, computed tomography, and magnetic resonance imaging. In addition, knowledge of the risk factors and the pathophysiologic, histologic, and epidemiologic features of fat accumulation may be useful for avoiding diagnostic pitfalls and planning an appropriate work-up in difficult cases.
[Show abstract][Hide abstract] ABSTRACT: To retrospectively determine the frequency and spectrum of findings and recommendations reported with whole-body computed tomographic (CT) screening at a community screening center.
This HIPAA-compliant study received institutional review board approval, with waiver of informed consent. The radiologic reports of 1192 consecutive patients who underwent whole-body CT screening of the chest, abdomen, and pelvis at an outpatient imaging center from January to June 2000 were reviewed. Scans were obtained with electron-beam CT without oral or intravenous contrast material. Reported imaging findings and recommendations were retrospectively tabulated and assigned scores. Descriptive statistics were used (means, standard deviations, and percentages); comparisons between subgroups were performed with univariate analysis of variance and chi(2) or Fisher exact tests.
Screening was performed in 1192 patients (mean age, 54 years). Sixty-five percent (774 of 1192) were men and 35% (418 of 1192) were women. Nine hundred three (76%) of 1192 patients were self referred, and 1030 (86%) of 1192 subjects had at least one abnormal finding described in the whole-body CT screening report. There were a total of 3361 findings, with a mean of 2.8 per patient. Findings were described most frequently in the spine (1065 [32%] of 3361), abdominal blood vessels (561 [17%] of 3361), lungs (461 [14%] of 3361), kidneys (353 [11%] of 3361), and liver (183 [5%] of 3361). Four hundred forty-five (37%) patients received at least one recommendation for further evaluation. The most common recommendations were for additional imaging of the lungs or the kidneys.
With whole-body CT screening, findings were detected in a large number of subjects, and most findings were benign by description and required no further evaluation. Thirty-seven percent of patients had findings that elicited recommendations for additional evaluation, but further research is required to determine the clinical importance of these findings and the effect on patient care.
[Show abstract][Hide abstract] ABSTRACT: LEARNING OBJECTIVES
1) To review the current role of MR imaging in pre-liver transplant evaluation 2) To discuss how MR findings affect patient management and surgical approach 3) To learn optimal MR techniques for preoperative transplant evaluation.
MR imaging plays an increasingly important role in the preoperative evaluation of orthotopic liver transplant candidates in several liver transplant centers. MR may offer superior sensitivity and specificity for diagnosis of liver pathology that determine liver transplant candidacy. State of the art MR pulse sequences enable comprehensive evaluation of vascular and biliary anatomy and liver parenchyma in a single examination. In this educational exhibit, we will specifically discuss: 1. MR assessment of liver anatomy and anatomic variations that may alter surgical approach or transplant candidacy 2. MR imaging findings that accelerate or exclude liver transplant 3. Optimal MR techniques for pre-operative evaluation 4. Multi-modality imaging and histopathogical correlation.
Radiological Society of North America 2005 Scientific Assembly and Annual Meeting; 12/2005